1. Field of the Invention
This invention relates to the fabrication of a laminated assembly and in particular to a drive arrangement for a laminate prepress assembly which allows for misalignment between the laminate and the prepress assembly.
2. Technical Considerations
A conventional laminated windshield includes a plurality of glass plies adhered to each other by a thermoplastic interlayer. In fabricating the windshield, the glass sheets are cut and bent to shape, the interlayer is positioned between the plies, and the entire assembly is subjected to elevated temperatures and pressures to laminate the assembly and form a unitary structure. Prior to lamination, the assembled windshield is typically processed to preliminarily adhere the glass plies to the interlayer and remove a portion of the air between the plies. One common apparatus used to perform the preliminary adhesion step is a prepress roll assembly which includes a plurality of vertically disposed, opposing roll segments that apply pressure to opposing major surfaces of the windshield assembly to squeeze the air out from between the glass and interlayer plies and adhere the glass to the interlayer. The rolls may be mounted on a rotating frame that allows the entire roll assembly to rotate about a horizontal axis, generally perpendicular to the direction of travel of the windshield through the opposing rolls, to more effectively apply pressure to the windshield without overstressing the glass plies.
The opposing rolls are aligned relative to each other such that the line of contact between the pairs of opposing rolls generally conforms to the corresponding transverse curvature of the windshield assembly. To continuously move the windshield assembly between the rolls, one or more of the roll segments is driven to advance the windshield assembly. The drive rolls are generally set in a fixed position and the remaining rolls are positioned relative to the fixed drive roll along the transverse curvature of the windshield assembly It has been observed that minor variations in the orientation of the windshield assembly relative to the prepress roll assembly as it is initially engaged by the fixed drive rolls, and in particular vertical misalignment between the leading edge of the windshield relative to the elevation of the drive rolls, can overstress the annealed windshield glass and increase the possibility of glass breakage during the prepressing operation.
It would be advantageous to have a drive arrangement for the prepress assembly drive rolls that allows the vertical position of the drive rolls to vary in response to minor vertical variations in the orientation of the windshield assembly as it initially enters and is pressed between the prepress rolls.